1. Field
Adhesive compositions are provided and more specifically adhesive compositions useful in the die attach process. The adhesive compositions exhibit excellent adhesive film release and die attach properties while also exhibiting void-free coverage in die attach applications.
2. Related Technology
Adhesive compositions play a prominent role in many industrial applications. For example, in the electronics industry, packaging engineers faced with increased challenges of finding new and better ways of creating and attaching dies during the dicing and subsequent die placement processes often rely on adhesive compositions to secure a silicon wafer to a dicing substrate during the dicing process and also to secure the individual diced chips to a circuit board or other substrate during die placement. Numerous adhesive compositions have been proposed for use in such die attach processes, including those described in one or more of U.S. Pat. No. 7,162,110 (Kohinata et al.), U.S. Pat. No. 7,312,534 (Santos et al.), and U.S. Pat. No. 7,176,044 (Forray et al.).
Those adhesives generally include a curable base component and one or more additives that provide the composition with unique properties. For example, additives are known to improve conductivity, reduce cure time, and provide a stronger interface bond after die placement has occurred. However, these adhesives do not adequately address certain problems associated with some of the current operations in the die attach industry.
For example, dicing die attach films, which are composed of a dicing tape layer and an adhesive layer on top of the tape layer, are increasingly being used in the dicing and die attach process. In use, a pre-diced silicon wafer is placed onto the adhesive layer of such a film, dicing of the wafer and the adhesive layer is completed, and the individual chip dies are removed from the tape layer of the film using conventional die pickup methods. Ideally, the layer of adhesive, which is also diced during the dicing process, transfers from the dicing tape to the chip die so that the chip die can subsequently be placed directly at another location without first dispensing a new layer of adhesive on the chip die or at the new placement location.
However, because of the nature of the adhesives currently used to form the adhesive layer in these dicing die attach films, adequate transfer of the adhesive from the dicing tape layer to the chip die surface does not always occur. Furthermore, because the adhesives used in the adhesive layer are composed of high molecular weight resins, the flow properties of such adhesives are oftentimes insufficient to create a void-free bond interface between the chip die and the substrate after the subsequent die placement and curing steps for die attachment.
Thus, there remains a need for novel adhesive compositions which include additives that provide unique advantages over those adhesive compositions that are currently known, particularly adhesives that better facilitate the transfer of the adhesive layer to the die during the die pickup process and allow for the formation a void-free bond after die placement.